Persian walnut tree named ‘Robert Livermore’

ABSTRACT

A new and distinct Persian Walnut Tree (i.e.,  Juglans regia ) is provided. Jumbo walnuts are produced having thick well-filled hulls. There is little walnut size variation in a given harvest. The kernels are easy to remove and display a distinctive atypical red-purple pellicle. The resulting walnut crop commonly can be harvested from a young tree prior to that of the ‘Chandler’ cultivar U.S. Plant Pat. No. 4,388) at Davis, Calif. The walnut kernels in view of their distinctive naturally-occurring festive red-purple pellicle are particularly suited for consumption at parties, holidays, or other special occasions.

SUMMARY OF THE INVENTION

The new Juglans regia Walnut Tree of the present invention was createdat Davis, Calif. during 1991 by a controlled cross of the ‘Howard’cultivar U.S. Plant Pat. No. 4,405) and the ‘Purpurea’ cultivar(non-patented in the United States). See U.S. Plant Pat. No. 4,405 forthe ancestry of the ‘Howard’ parent. The ‘Purpurea’ parent used in thecross also identified as ‘RX1088’ and was obtained from the Walnutcollection of E. Germain (Institut National de la Recherche Agronomique,Station de Recherches d'Arboriculture Fruitiere, Bordeaux, France). TheKernels of the ‘Howard’ parent bear a typical seed coat that is amber orlight amber. The kernels of the ‘Purpurea’ cultivar possess areddish-brown seed coat. The parentage of the new cultivar can besummarized as follows:

‘Howard’×‘Purpurea’.

Seeds from the cross were collected and planted and the resulting treeswere carefully observed. A single plant of the new cultivar was selectedin view of its highly distinctive combination of characteristics. Thisselection initially was designated ‘91-75-15’.

It was found that the new Juglans regia cultivar of the presentinvention exhibits the following combination of characteristics:

(a) Forms jumbo-sized walnuts with little size variation in a givenharvest which possess strong thick well-filled shells and easy to removekernels,

(b) Forms kernels which display a distinctive red-purple pellicle,

(c) Bears fruit laterally, and

(d) Yields a walnut crop that commonly can be harvested from a youngtree prior to that of the ‘Chandler’ cultivar (U.S. Plant Pat. No.4,388) at Davis, Calif.

The new cultivar of the present invention has been propagated bygrafting at Davis, Calif. on ‘Paradox’ hybrid rootstock. The distinctivecharacteristics of the new cultivar have been found to be stable and aretransmitted from one generation to another following such a sexualpropagation.

The new cultivar of the present invention has been named the ‘RobertLivermore’ cultivar. Rober Livermore was a supporter of the WalnutImprovement Program at the University of California for many years andis honored through the naming of this plant.

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

The accompanying photographs show, as true as is reasonably possible tomake the same in color illustrations of this character typicalillustrations of the new cultivar of the present invention while graftedon ‘Paradox’ hybrid rootstock. The trees were three years of age andwere grown at Davis, Calif. The trees of FIGS. 1, 2 and 3 were graftedduring the Spring of 1998 and were photographed during November, 1999.

FIG. 1—shows a typical young trees of the ‘Robert Livermore’cultivarwhere the trunk portions of the trees have been whitewashed to minimizesun damage.

FIG. 2—shows a near view of the typical trunk and lateral branches ofthe ‘Robert Livermore’ cultivar. The lower trunk portion has beenpainted white.

FIG. 3—shows a near view of typical leaves and stem of the ‘RobertLivermore’ cultivar.

FIG. 4—shows typical views of the walnuts of new cultivar. From left toright are shown two kernel halves, a walnut in the shell, and a walnutin the shell wherein half of the shell has been removed. The photographwas prepared during March 1998 while observing the walnut harvest fromthe previous growing season. The distinctive red-purple pellicle isreadily apparent once the shell is removed.

FIG. 5—again presents at the upper right the subject matter of FIG. 4and includes for comparative purposes similar views of four non-releasedand non-patented experimental varieties ‘90-27-21’, ‘90-27-23’,‘90-31-16’ and ‘91- 96-3’, the ‘Howard’ cultivar (U.S. Plant Pat. No.4,405), the ‘Chandler’ cultivar (U.S. Plant Pat. No. 4,388), and the‘Tulane’ cultivar U.S. Plant Pat. No. 8,268).

DETAILED DESCRIPTION

The description is based upon Walnut Trees propagated by grafting on‘Paradox’ hybrid rootstock and growing in the field at Davis, Calif.

The Munsell color chart is used in the identification of color. Also,common color terms are to be accorded their ordinary dictionarysignificance.

Botanical classification: Juglans regia, ‘Robert Livermore’.

Female parent.—‘Howard’ cultivar (U.S. Plant Pat. No. 4,405).

Male parent.—‘Purpurea’ (non-patented in the United States).

Plant: The growth habit of the tree is illustrated in FIGS. 1 and 2. Athree year-old tree typically displays a height of approximately 18 feetand a canopy diameter of approximately 10 feet. The trunk diameter at 4feet above the ground is approximately 60 mm. The bark (as illustrated)is typical of Juglans regia. The young bark is smooth and dark brown(5.5 YR 3.5/1.8 gy. yBr.) with numerous raised white lenticels. Themature bark is smooth and gray (6.7Y 7.4/0.2 1.Gy.) with few lenticlesand some cream-colored vertical marking. On one to two year-old barkthere commonly are approximately 10 lenticels per square cm that areapproximately 0.5 to 3.5 mm in size and 9.7YR 6.4/2.5 1.gy.yBr. incoloration.

Foliage: The attractive dark green foliage is illustrated in FIG. 3 andis typical of Juglans regia. Leaf out has occurred approximately thesame time as the ‘Chandler’ cultivar (U.S. Plant Pat. No. 4,388). Leafout for young trees of the new cultivar during 1994 to 1998 has occurredon April 5th on average. For comparative purposes the ‘Chandler’cultivar leafed out on April 3rd on average from 1988 to 1998. The leafout for young trees of the new cultivar has averaged approximately 20days after that of the ‘Payne’ cultivar (non-patented in the UnitedStates). It has not been determined whether the time of leafing of thenew cultivar will shift as the tree further matures. The typical leafcoloration is moderate olive green, 7.5 GY 4/4 on the upper surface and5 GY 5/6 on the under surface. The typical sepal coloration is moderateolive green, 5 GY 4/4. The leaves are pinnately compound andapproximately 40 cm in length and approximately 25 cm in width. The leafmargins are entire. The typical petiole coloration is 2.5 GY 6/8 strongyellow green, and the typical leaf vein coloration is 2.5 GY 6/8 strongyellow green. The petioles commonly are approximately 11 cm in length tothe first leaflet and 30 cm in length to the base of the terminalleaflet. The typical petiole diameter is approximately 3.5 mn.

Infloresence: The new cultivar has proven to be relatively precocious.First bloom has occurred at an age of 3 years or 4th leaf. From 1995 to1998 first bloom has occurred on young trees of the new cultivar onApril 21 on average, peak bloom on April 26th on average, and last bloomon May 1st on average. For comparative purposes the ‘Chandler’ cultivarfrom 1988 to 1998 exhibited first bloomed on April 15th on average, peakbloom on April 22nd on average, and last bloom on April 29th on average.It has not been determined whether the time of blooming of the newcultivar will shift as the tree further matures. The flowers a typicalof Juglans regia in number and shape with two flowers per inflorescenceborne at both the terminal and lateral positions on the current year'sgrowth. This makes possible increased yields over walnut cultivars thatbear fruit terminally. A typical flower diameter is approximately 5 to 7mm at anthesis. The floral organs are typical of Juglans regia. Theflower fragrance is typical of Juglans regia and is not noticeablydifferent than the foliage fragrance. Approximatley 90 percent of thelateral buds are fruitful.

Walnuts: The new cultivar commonly harvests prior to the ‘Chandler’cultivar. During 1998 young trees of the new cultivar were ready forharvest on October 2nd. This compares to October 12th for the ‘Chandler’cultivar during 1998. Jumbo-sized walnuts are formed in good yield whichexhibit a flavor typical of commercial walnut cultivars. The nutshell is10 YR 5/6 strong yellowish brown in coloration. As illustrated in FIGS.4 and 5, the kernels display a distinctive red-purple pellicle which canbe used to readily distinguish the new cultivar. Such colorationtypically approaches 41-42 of the Munsell color scale. The new cultivaris regular bearing (not alternate bearing). However, as will be apparentto those skilled in walnut production, the size of the walnuts that areproduced will vary somewhat with the yield achieved during a givengrowing season. During the current growing season the walnuts averagedapproximately 36.4 mm. in length and approximately 35.8 mm. in width.The shell is strong, thick, and well-filled and the kernel is easy toremove. The kernel commonly weighs approximately 7.1 g. on average andcommonly consists of approximately 48 percent by weight on average ofthe average total walnut weight of approximately 14.8 g. These valuesare based upon four year averages of ten walnut samples obtained fromyoung trees and are considered to be fairly typical of commercialwalnuts. The walnut yield is good but tends to be lower than that of the‘Chandler’ cultivar during observations to date. Typical kerneldimensions are approximately 28 mm in length and approximately 29 mm inwidth.

Hardiness: Trees have withstood temperatures of 21° F. in late December.

Disease resistance and suseptibility: Susceptibility to walnut blightXanthomonas campestris var. juglandis damage is average. Susceptibilityto mite damage is greater than average. No other unusual resistance orsusceptibility to insects or diseases has been observed to date.

Usage: The new cultivar of the present invention provides distinctivekernels having a naturally-occurring festive red-purple appearance thatare particularly suited for consumption at parties, holidays, or otherspecial occasions.

We claim:
 1. A new and distinct cultivar of Juglans regia tree havingthe following combination of characteristics: (a) forms jumbo-sizedwalnuts with little size variation in a given harvest which possessstrong thick well-filled shells and easy to remove kernels, (b) formskernels which display a distinctive red-purple pellicle, (c) bears fruitlaterally, and (d) yields a walnut crop that commonly can be harvestedfrom a young tree prior to that of the ‘Chandler’ cultivar (U.S. PlantPat. No. 4,388) at Davis, Calif.;